Pyrolysis kinetics and residue characteristics of petrochemical industrial sludge

This study investigated the pyrolysis characteristics of sludge from wastewater treatment plants in the petrochemical industry and focused on the pyrolysis kinetics, elemental composition of residue, and volatile organic compounds (VOCs) of exhaust gas. As pyrolysis temperature increased to 773 K, the increasing rate of crude oil production tended to a stable condition. The result indicated that the optimal temperature of crude oil and water mixed production was 773 K. When pyrolysis temperature increased from 673 to 973 K, carbon, oxygen, nitrogen, and hydrogen concentrations of residue decreased and the sulfur concentration of residue increased. The concentrations of benzene, toluene,ethylbenzene, and styrene increased by the increasing pyrolysis temperature. We found that the reaction order of sludge pyrolysis was 2.5 and the activation energy of the reaction was 11.06 kJ/mol. We believe that our pyrolysis system is transitional between devolatilization and combustion.     

Pyrolysis Kinetics and Residue Characteristics of Petrochemical Industrial Sludge

ABSTRACT

This study investigated the pyrolysis characteristics of sludge from wastewater treatment plants in the petrochemical industry and focused on the pyrolysis kinetics, elemental composition of residue, and volatile organic compounds (VOCs) of exhaust gas. As pyrolysis temperature increased to 773 K, the increasing rate of crude oil production tended to a stable condition. The result indicated that the optimal temperature of crude oil and water mixed production was 773 K. When pyrolysis temperature increased from 673 to 973 K, carbon, oxygen, nitrogen, and hydrogen concentrations of residue decreased and the sulfur concentration of residue increased. The concentrations of benzene, toluene, ethylbenzene, and styrene increased by the increasing pyrolysis temperature. We found that the reaction order of sludge pyrolysis was 2.5 and the activation energy of the reaction was 11.06 kJ/mol. We believe that our pyrolysis system is transitional between devolatilization and combustion.     

热解含油污泥制备吸附剂及热解过程的优化

为资源化利用油田含油污泥,对高含油的孤岛采油厂含油污泥进行热解处理研究,以苯酚吸附值为基准对热解工艺过程进行优化,并采用ICP-MS、元素分析仪、气相色谱质谱仪和SEM对热解油品和残渣性质进行分析;正交实验和单因素实验结果相一致,热解最佳工艺条件为:N2保护下,热解温度550℃,热解时间4 h,升温速率10℃/min,此时苯酚吸附值为29.26 mg/g。通过对热解残渣苯酚吸附值为基准进行正交实验极差分析,热解温度的影响最大,其次是热解时间,最后是加热速率。SEM结果显示,热解含油污泥制备的固体残渣具有丰富的微米孔,可将其制备成多孔固体吸附剂。初步研究结果表明,含油污泥热解处理实现了无害化和资源化目的,满足国家节能减排的战略要求和农用污泥排放标准。     

城市污泥热解中试系统集成一体化研究及运行效果评估

为了促进城市污泥热解工艺的工程化应用,组建了污泥热解系统、热解产物分离回收利用系统、废气净化排放系统于一体较完整的热解中试装置,在实现污泥有效处置的同时也实现了高值能源回收利用。中试工况优化,较好工况为：热解时间30-40 min,热解终温450-500℃,在此条件下,干化污泥（含水率5%）减量率为50%;热值为33.8 MJ/kg的热解油产率为17.1%左右。通过对中试运行效果的评估,得出热解油和热解气两者能量或污泥炭自身能量可供干化污泥热解本身所需能量,从而为推动污水污泥热解工艺的工程化利用提供了支持。     

石灰预处理和干发酵对稻草热解特性影响

深入研究生物质热解有助于热解机理的理解,利用热重分析来探讨石灰预处理和干发酵对稻草热解特性的影响。结果表明:预处理使木质素和半纤维素含量增加,而干发酵使VS、半纤维素和纤维素含量降低;预处理和干发酵改变稻草热解特性,但未改变稻草的热反应机理;热解一级动力学方程很好模拟稻草热解的主失重阶段,稻草热解活化能数值为42.3～47.8 kJ/mol,属于正常范围;预处理降低反应活化能,而干发酵增加反应活化能。这为秸秆及其干发酵残渣的气化提供了重要的设计依据。     

Bio-syngas production with low concentrations of CO2 and CH4 from microwave-induced pyrolysis of wet and dried sewage sludge

This paper assesses the feasibility of producing syngas from sewage sludge via two pyrolysis processes: microwave-induced pyrolysis (MWP) and conventional pyrolysis (CP). The changes in the composition of the produced gas as a function of the pyrolysis treatment and the initial moisture content of the sludge were evaluated. It was found that MWP produced a gas with a higher concentration of syngas than CP, reaching values of up to 94vol%. Moreover, this gas showed a CO2 and CH4 concentration around 50% and 70%, respectively, lower than that obtained in the gas from CP. With respect to the effect of moisture on gas composition, this was more pronounced in CP than in MWP. Thus, the presence of moisture increases the concentration of H2 and CO2 and decreases that of CO, especially when CP was used. In order to elucidate the behaviour of CO2 during the pyrolysis, the CO2 gasification kinetics of the char obtained from the pyrolysis were investigated. It was established that in microwave heating the gasification reaction is much more favoured than in conventional heating. Therefore, the low concentration of CO2 and the high concentration of CO in the microwave pyrolysis gas could be due to the self-gasification of the residue by the CO2 produced during the devolatilization of the sewage sludge in the pyrolysis process.     

油田采油污泥的热解动力学及其热解效果研究

以新疆克拉玛依油田采油污泥为对象,分别采用热重分析仪和小型流化床热解反应器研究了含油污泥的热解过程及其热解效果。结果表明,油泥热解主要经历了失水、轻质组分挥发、重组分快速热解失重和缓慢失重4个阶段,热解过程基本符合一级动力学方程,提高热解的升温速率,可使油泥的最大失重速率D_max、失重速率峰值温度θ_max、升温终点的最大失重率都随之增加,表现在动力学上,反映出表观活化能和碰撞频率因子的同时升高,即提高油泥热解转化率的同时也影响了热解效率。失水油泥用流化床热解,在热解温度600℃、反应时间3 min时,油泥回收率可达到87%。     

废旧电路板与碳酸钙共热解脱卤的研究

采用热重分析仪和石英管式炉热解反应器,分别对以酚醛树脂为基板的废旧电路板和混合碳酸钙后的废旧电路板进行热解实验研究,着重考察了添加碳酸钙后的酚醛树脂基板废旧电路板热解特性及添加量不同对卤素脱除效果的影响。实验结果表明,碳酸钙的加入对废旧电路板的降解行为和热解油的基本组成没有明显的影响,但热解油的各组分含量有所差异;随着热解温度的提高或者CaCO₃含量的增多,卤素可以更多地由有机卤向无机卤转变并束缚在固体残渣中,由此得到较好的脱卤效果。当60%PR-WPCBs与40%CaCO₃共热解,热解油中的溴化物也减少了7.6% 。在600℃等量CaCO₃与PR-WPCBs共热解时生成75.6%无机卤,其中70.62%束缚于固体残渣中,可见达到较好的脱卤效果。     

以粉煤灰和电石渣为催化剂的聚丙烯裂解模型研究

对粉煤灰和电石渣为催化剂的聚丙烯裂解进行模型研究.通过模型计算了裂解反应的表观活化能、频率因子、反应级数等.模型计算表明随着反应温度的升高反应速率增加,达到相同转化率所需反应时间减少.当剂塑比从0增加到30%时,聚丙烯裂解的活化能呈现降低的趋势,特别当剂塑比为30%时,其活化能降低约50%.说明粉煤灰和电石渣对聚丙烯裂解具有一定的催化效果.     

废印制线路板真空热解渣分选与组成分析的研究

在自行设计制备的真空热解炉中进行了废印制线路板的热解实验,得到固体、液体和气体产物。着重研究了热解固体渣中金属铜和非金属玻璃纤维的物理分选、热解固体渣分析及有氧煅烧对玻璃纤维纯度的影响。结果表明,物理分选效率很高,金属铜的回收率和纯度接近100%;热解固体渣含30.35%的铜、56.21%的玻璃纤维和13.45%的炭黑;有氧煅烧去除炭黑可得到高纯度的玻璃纤维。     

润滑油废白土的热解处理

以润滑油废白土为原料,利用电热解法,研究了热解终温、加热速率和CaO添加量对热解产物的影响。实验结果表明:热解终温对热解产物的影响最为显著。随着热解终温的升高,不凝气产量和产油率均迅速增加。当热解终温达到600℃时,其增加的速率逐渐缓慢增大。当控制热解终温为800℃、加热速率为16℃/min、CaO添加量为0.5%时,富氢气体产量为189.2 L/kg,气体中主要成分为H2和CH4,其含量分别为27.97%和41.64%;热解残渣含油率和重金属溶出物均低于标准规定值,热解油产率为10.98%,回收率为38.94%,其主要成分为汽油、柴油和重油3部分组成,分别含19.13%、31.35%和49.52%。     

Pyrolysis and GC/MS-analysis of brominated flame retardants in on-line operation

Flame retardants such as brominated diphenyl ethers (Bromkal 70-5-DE, FR 300 BA), 2,4,6-tribromophenol, pentabromophenol and hexabromobiphenyl were pyrolyzed at 600°C, 700°C, 800°C and 900°C in absence of oxygen in a SGE pyrojector, and the residues were analyzed by means of GC/MS in on-line operation. The pyrolysis of Bromkal 70-5-DE hereby yielded bromobenzenes (PBBz), bromophenols (PBP) and brominated dibenzofurans (PBDF). PBBz, bromonaphthalenes (PBN) and PBDF could be detected in the FR 300 BA pyrolysate, whereas brominated benzenes and dibenzodioxins formed during the pyrolysis of 2,4,6-tribromophenol. Unlike the pyrolysis of 2,4,6-tribromophenol, pentabromophenol pyrolysis produced mainly bromobenzenes along with traces of bromonaphthalenes, bromodioxins and bromodiphenyl ethers. The pyrogram of hexabromobiphenyl showed bromobenzenes and brominated biphenyls as key pyrolysate components.     

餐厨垃圾中典型组分的裂解液化特征研究

利用实验室规模的实验装置管式加热炉进行餐厨垃圾热解实验,实验分析了反应温度对餐厨垃圾热解产物分布的影响,米饭、白菜、猪肉、塑料和纸5种原料在最佳温度下可实现热解油质量产率的最大化,分别为45.02%、24.55%、61.19%、73.77%和24.86%。其中,米饭和白菜热解油含水率较高,可达到30%~40%,将含水率降到15%后,测定热值分别为25.51 MJ/kg和17.75 MJ/kg。塑料和纸混合热解时,塑料热解过程的放热效应可缩小纸的热解温度区间,增加热解油产量。红外光谱分析厨余热解油包含多种含氧有机物。通过气质联用仪(GC-MS)分析塑料热解油和塑料与纸混合热解油在180℃以下蒸馏出的液相产物,主要组分为烷烃和烯烃,从成分和热值分析,与汽油、柴油相近。     

油田含油污泥热解制备烟气脱硫剂

为实现油田含油污泥深度资源化,针对高含油的孤岛采油厂含油污泥采用热解处理,回收油气资源的同时将热解残渣制备成烟气脱硫剂。以苯吸附值和热解残渣含油率为基准对热解工艺进行了优化,对热解油品和残渣进行分析,热解残渣经过后续处理进行了烟气脱硫性能评价。通过正交实验得到热解最佳工艺条件为:氮气保护下,热解温度550℃,热解时间4h,升温速率10℃/min。此时苯吸附值为60.12mg/g,热解残渣含油率为0.29%。最佳工艺条件下,热解油品产率可达10%左右,回收率大于65%,热裂解作用明显,热解油品的品质较好,产生的不凝气体可以作为洁净燃料气;热解残渣经过后续处理,可用于脱除烟气中的SO2,吸附脱硫能力较好,穿透硫容达到3%以上。     

Pyrolysis of humic acids from digested and composted sewage sludge

Humic acids (HAs) were extracted from four digested sewage sludge samples composted for four months, one, two and four years. HAs were pyrolyzed at three different temperatures applying both conventional and in situ methylation (ISM) pyrolysis. The pyrolysates were analyzed using gas chromatography-mass spectrometry (GC/MS). Derivatization (ISM) and pyrolysis temperature had dramatic effects on the composition and relative amounts of the pyrolysates. Among the derivatized HA fragments aliphatic compounds prevailed under all the pyrolysis conditions tested. Aromatic substances consisting mainly of guaiacyl-type compounds were detected in higher abundances only at elevated temperatures. Without ISM the contribution of aromatic structures to the total pyrogram was considerably greater than that of the aliphatics. Increase of the pyrolysis temperature from 450 degrees C to 600 degrees C had smaller effect on the proportions and composition of the compounds studied than increase from 350 degrees C to 450 degrees C.     

中孔分子筛AI-MCM-41催化裂解聚烯烃反应研究

采用水热合成法制备了不同硅铝比的中孔分子筛AI-MCM-41，将其应用于高密度聚乙烯（HDPE）和聚丙烯（PP）的催化裂解反应。通过改变硅铝比、反应温度和催化剂用量，对Al-MCM-41催化HDPE和PP裂解反应的规律进行了探讨，研究表明，HDPE裂解反应受硅铝比的影响较大；而对于PP裂解反应，硅铝比在一定范围内对催化剂活性的影响不明显。另外，与热裂解和HZSM-5小孔分子筛的催化裂解结果进行了比较，结果证明A1-MCM-41具有较高的催化活性和较高的液体产物收率，尤其适合于空间位阻较大的PP的催化裂解反应。     

不同升温速率下城市污水污泥热解特性及动力学研究

利用差热-热重分析法和Coats-Redfern积分法,对杭州某污水处理厂污泥在不同升温速率下的热解特性及反应动力学特征进行研究。实验结果表明,热解温度从室温升至900℃时,污泥热解过程可分为4个失重阶段;升温速率对污泥热解转化率、挥发分析出温度以及最大失重率等热解特性参数都有显著影响。升温速率越高污泥最大失重率越大;而较低的升温速率延迟了污泥热解反应时间,导致污泥失重量相对较大。根据Coats-Redfern积分法计算结果,污泥在氮气氛围下的热解反应为二级反应模式。提高升温速率可显著增加污泥热解的表观活化能和频率因子。     

船舶塑料垃圾热解特性及动力学分析

利用热重分析(TGA)研究船舶塑料垃圾在不同升温速率和不同气氛下的热解特性,并得到了热解动力学参数。结果表明,船舶塑料垃圾的热解过程主要有3个阶段,比一般塑料热解复杂;随着升温速率增大,最大热解速率和最大热解速率温度等热解特性参数也增大,反应变得更剧烈;N2/CO2比为4∶1时,热解反应进行得最完全,固体残留率最少。动力学分析表明,采用3个连续一级反应模型能很好地拟合实验数据;不同的升温速率和气氛比对反应各阶段活化能均有不同程度的影响。     

中孔分子筛Al-MCM-41催化裂解聚烯烃反应研究

采用水热合成法制备了不同硅铝比的中孔分子筛A l-MCM-41,将其应用于高密度聚乙烯(HDPE)和聚丙烯(PP)的催化裂解反应。通过改变硅铝比、反应温度和催化剂用量,对A l-MCM-41催化HDPE和PP裂解反应的规律进行了探讨,研究表明,HDPE裂解反应受硅铝比的影响较大;而对于PP裂解反应,硅铝比在一定范围内对催化剂活性的影响不明显。另外,与热裂解和HZSM-5小孔分子筛的催化裂解结果进行了比较,结果证明A l-MCM-41具有较高的催化活性和较高的液体产物收率,尤其适合于空间位阻较大的PP的催化裂解反应。     

城郊乡村生活垃圾衍生燃料热解特性研究

将城郊乡村生活垃圾加工成粒径6.0 mm左右的垃圾衍生燃料(RDF),采用热重(TG)分析和红外光谱等研究其热解特性.结果表明:(1)在RDF挥发分阶段和生物质挥发分阶段,助燃添加剂处于活泼分解阶段,加入了30％(质量分数)秸秆、玉米芯等生物质作助燃添加剂后的RDF(以下简写为混合RDF)分子碎片正发生内部氢重排,总体挥发分产物较多,并且有明显的二次裂解,失重提高到4.85 mg,失重率约提高12％.在RDF与生物质重叠的碳固定阶段,助燃添加剂失重率有一定提高,热重微分(DTG)峰值速率增加,为RDF碳固定阶段的进一步热解提供了良好的支持.(2)快加热产气速率均大于慢加热.(3)热解终温越高,越有利气体析出.(4)RDF的热解固体产率随着热解终温的升高而降低,在850℃时为31.9％;热解气体产率随着热解终温升高而迅速升高,在850℃时可达49.8％.(5)根据红外光谱图,城郊乡村生活垃圾加工成的RDF中所含的氯元素基本上以HCl形式释放.(6)一级动力学反应可以准确地描述物料热解过程.